In the manufacture of communication cables, each communications channel is usually associated with a pair of wires that are twisted one about the other to provide a degree of shielding so as to minimize reception and emission of spurious signals by electronic or magnetic radiation. Hundreds or thousands of these twisted pairs are often combined in a single cable that can be hung from poles, pulled through conduit buried in the ground, or can be buried directly in the ground. With so many twisted pairs in close proximity within a single cable, steps must be taken to prevent crosstalk between one twisted pair and another. Such crosstalk within the cable is minimized by having the twisted pairs of many different twist lengths, typically varying from 1.8 inches per twist to 6.1 inches per twist in increments of 1/10 inch. With many different twist lengths within a cable, radiations from one twisted pair are cancelled at various points on another twisted pair due to the changing phase between the twisted lengths of any two pairs. Efforts must then be made when "laying up" a cable to keep twisted pairs of the same twist length reasonably remote from one another to minimize crosstalk resulting from long, parallel lengths of identical twist length. This requires extra care in the preparation and assembly of cable.
Twisting machines customarily provide direct gearing between the wire pulling mechanism and the twister carriage or flier which twists one wire about the other. These gears are readily changeable to vary the ratio between pulling and twisting so as to produce the wide range of twist lengths desired. These gear-driven machines can tend to be noisy, especially in large numbers.